Understanding the expression and interaction of Rph genes conferring seedling and adult plant resistance to Puccinia hordei in barley

Figures & data

Table 1. List of barley ‘Bowman’ near-isogenic lines (NILs)* and genotypes screened for response to Puccinia hordei at three different temperature regimes in the greenhouse

Parents	Pedigree
Bowman (B) (PI 483237)	Klages//Fergus/Nordic/3/ND1156/4/Hector
B+Rph1.a	Bowman*6/Sudan
B+Rph2.b	Bowman*8/Reka I
B+Rph3.c	Bowman*11//Estate/3.2 uz als
B+Rph4.d	MM Gold/6*Bowman
B+Rph5.e	Magnif 102/8*Bowman
B+Rph6.f	Bowman*8/Bolivia
B+Rph9.i	Bowman*8/Hor 2596
B+Rph11.p	Bowman*6/Clipper BC67
B+Rph12 (9.z)	Bowman*9/Triumph
B+Rph13.x	Bowman*7/PI 531849
B+Rph14.ab	Bowman*5/PI 584760
B+Rph15.ad	PI 355447/8*Bowman
Flagship (Rph20)	Chieftan/Barque//Manley/VB9104
Yerong (Rph23+Rph2)	M22/Malebo
ND24260 (Rph24)	ND19869-1//ND17274/ND19119

* Originally developed by J.D. Franckowiak and colleagues at North Dakota State University (Chicaiza 1996; Caffarel 2005).

Fig. 1 Schematic development of Rph12 (9.z) and Rph20 gene combination stocks. Other Rph combinations were developed in this study using the same genetic model

Table 2. Responses of barley near-isogenic lines (NILs) against pathotypes 200 P− and 5457 P+ of Puccinia hordei at three post-inoculation temperatures in the greenhouse under natural lighting

Pathotype	200 P−			5457 P+
Genotype/Temperature	26 ± 2℃	22 ± 2℃	18 ± 2℃	26 ± 2℃	22 ± 2℃	18 ± 2℃
Bowman	3+	3+	3+	3+	3+	3+
B+Rph1.a	;1+C	;12+CN	;12+CN	33+	3+	3+
B+Rph2.b	;1+C	23C	22+	3=	3+	3+
B+Rph3.c	;CN	;+C	;+	33+	3+	3+
B+Rph4.d	3+	;12+C	;12+C	3+	3+	3+
B+Rph5.e	;1++CN	;1+C	;12+C	;CN	;+CN	;++C
B+Rph6.f	;1++CN	;1+C	;12+C	;CN	;+C	;+C
B+Rph9.i	;1+C	;12+CN	;12+C	3+	3+	3+
B+Rph12 (9.z)	;1+C	;1+C	;1+C	3+	3+	3+
B+Rph11.p	1+2+C	;12-C	;1++CN	3	3+	3+
B+Rph13.x	;+N	;+C	;+C	;1+CN	;1+CN	;1+C
B+Rph14.ab	23C	2+3+	;12+CN	;12+C	;12+C	;C
B+Rph15.ad	;+CN	;+CN	;+CN	;+CN	;+CN	;+CN
Flagship (Rph20)	33+	3	2+C	33+	3=	2+C
Yerong (Rph23+Rph2)	;12C	2C	2C	3+	3+	3+
ND242620 (Rph24)	3+	3+	3+	3+	3+	3+

Infection types are based on a ‘0’–‘4’ scale (Park and Karakousis 2002) and presented as the modal value. ‘0’ = no visible uredinia or other macroscopic sign of infection, ‘;’ (fleck) = necrotic flecks of varying sizes; ‘1’ = restricted small uredinia surrounded by necrosis, ‘2’ = small to medium uredinia often surrounded by chlorosis or necrosis, green island may be surrounded by chlorosis or necrosis, ‘3’ = medium-sized uredinia that may be associated with chlorosis or rarely necrosis, ‘3+’ to 4 = large uredinia without chlorosis or necrosis with abundant sporulation. The letters ‘C’ and ‘N’ indicate chlorosis or necrosis, respectively; ‘+’ and ‘−’ indicate higher and lower infection types, respectively, than the normal.

Table 3. Frequency of segregation (HR, Seg and HS)* observed among BC_nF₃ families of barley for each gene combination when inoculated with pathotypes 200 P− or 5457 P+ of Puccinia hordei.

Population	Pathotype used	HR	Seg	HS	χ^2	p
Rph1.a+Rph20	200 P−	9	20	10	0.07	0.96
Rph2.b+Rph20	200 P−	14	14	12	3.80	0.14
Rph3.c+Rph20	200 P−	11	16	13	1.80	0.40
Rph4.d+Rph20	200 P−	10	20	9	0.07	0.96
Rph5.e+Rph20	5457 P+	11	18	11	0.40	0.81
Rph6.f+Rph20	200 P−	10	20	10	0	1
Rph9.i+Rph20	200 P−	9	21	10	0.15	0.92
Rph12 (9.z)+Rph20	200 P−	9	22	8	0.69	0.70
Rph13.x+Rph20	5457 P+	11	18	11	0.40	0.81
Rph15.ad+Rph20	5457 P+	15	20	5	5	0.08

χ² table value at p 5% = 5.99 at 2 df and p 1% = 9.21 at 2 df.

*HR = homozygous resistant, Seg = segregating, HS = homozygous susceptible.

Table 4. Infection type (IT) response of barley parents and gene combinations using avirulent pathotypes (200 P− or 5457 P+) of Puccinia hordei.

Gene combination	Donor parent	Recurrent parent	Pathotype used	IT response of parent (donor/recurrent)	IT response of combination
Rph1.a+Rph20	B+Rph1.a	Flagship	200 P−	;1-CN/3+	;+CN
Rph2.b+Rph20	B+Rph2.b	Flagship	200 P−	;12+CN/3+	;1-CN
Rph3.c+Rph20	B+Rph3.c	Flagship	200 P−	;+CN/3+	;+CN
Rph4.d+Rph20	B+Rph4.d	Flagship	200 P−	;12CN/3+	;1CN
Rph5.e+Rph20	B+Rph5.e	Flagship	5457 P+	;1+CN/3+	;N
Rph6.f+Rph20	B+Rph6.f	Flagship	200 P−	;1+CN/3+	;1+CN
Rph9.i+Rph20	B+Rph9.i	Flagship	200 P−	;12C/3+	;1C
Rph12 (9.z)+Rph20	B+Rph12 (9.z)	Flagship	200 P−	;+C/3+	;1 + C
Rph13.x+Rph20	B+Rph13.x	Flagship	5457 P+	;1+CN/3+	;1 + CN
Rph15.ad+Rph20	B+Rph15.ad	Flagship	5457 P+	;1+CN/3+	;+CN

The IT responses of parents and combinations are presented as the modal value.

Fig. 2 (Colour online) Rph5.e+Rph20 combination lines of barley showing improved resistance in contrast to parental line Bowman+Rph5.e and ‘Flagship’ (Rph20) when tested with avirulent pathotype 5457P+ (A) and virulent pathotype 220 P+ +Rph13 (B) of Puccinia hordei. ‘Bowman’ was used as a susceptible control

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